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Counterfeit Coin Detection

by Reid Goldsboro

IN A NUTSHELL:Counterfeit coins are an unavoidable reality in the numismatic marketplace, particularly with ancient coins though with modern coins as well. Learning the diagnostics of coin forgeries as well as the characteristics of authentic coins, buying from reputable dealers, avoiding sellers you don 't know who create "private" eBay actions, avoiding sellers in any venue with a no-return policy claiming they 're selling coins from an estate, and buying smart in general can minimize your exposure to coin counterfeits. The study of counterfeits, along with protecting you, can also be interesting in itself.

Perhaps the most frequent question collectors of ancient coins are asked by non-collectors is, "How do you know it 's real?" The disconcerting answer sometimes is, "You don 't." Not with all coins, not with certainty.

The fact is, significant numbers of counterfeit ancient coins are sold as authentic coins. But counterfeiting can be a problem for collectors of modern coins too, with the large numbers of fakes made in China being a particularly big challenge today. Further, modern as well as ancient coins are sometimes altered from a common variety to a rare one, a form of counterfeiting. The issue of counterfeit coins shouldn 't deter you from coin collecting. The number of fakes on the market is dwarfed by the number of genuine coins. But coin counterfeiting is an issue that any savvy collector needs to face.

Counterfeit coin detection, particularly with ancient coins, is as much art as science. Because they were struck by hand and because of the wide variability of their designs, even the best experts are sometimes fooled. Some of the most prestigious dealers in the world bought large numbers of counterfeit ancient coins as authentic coins at the 1999 and 1988 New York International Numismatic Conventions, which were only later discovered to be coin forgeries. Many dealers contacted buyers and refunded their money, but dealers returned these fakes to their sources, and later large numbers of them still entered the market as authentic coins.

The most frequently seen counterfeit or altered U.S. coins, according to PCGS 's 2004 book Coin Grading and Counterfeit Detection, include:

Unless you 're a specialist, you should think carefully about buying any of the above coins unless they 're in the slab of a legitimate grading/authentication service, such as PCGS, NGC, ANACS, or ICG. But the Chinese forgery workshops are now making passable fakes of common, inexpensive coins, so you need to be careful here too, with buying from an expert dealer being a good way to minimize risk.

With ancient coins, too, low-cost specimens are counterfeited today. As Wayne Sayles points out in his 2001 book Classical Deception: Counterfeits, Forgeries and Reproductions of Ancient Coins, you can no longer assume that it 's impractical for someone to make deceptive fakes of inexpensive coins, including someone living in relative poverty in Eastern Europe who may have advanced engraving skills or even a university degree in metallurgy.

Counterfeits Online

Fakes of modern and ancient coins sold as authentic coins on eBay and at some Web sites are a frequent problem, though if you follow the online coin discussion groups, these coin forgeries are frequently exposed.

Chinese fakes of U.S. and world coins are a particular problem today. One Chinese counterfeiter, the Big Tree Coin Factory of Fujian, China, has put up on eBay thousands of coin "replicas," marked as copies, only if you inquire you can buy the same pieces unmarked. This forgery factory has thus been using eBay as a front for moving what are likely untold thousands of counterfeit coins into the coin market. Some of these fakes are more convincing than others, of the correct alloy and in the correct weight tolerance. This forgery workshop makes high-tech die transfer fakes, using authentic coins to make the dies, using a coin press to mint the forgeries, and artificially aging them. Susan Headley in Coin World and at About.com has done a good job documenting this particular forgery operation.

Another huge counterfeit scam on eBay involved thousands of ancient coin auctions ran on eBay for an astounding four years in the early 2000s involving a forger from the Toronto, Canada, area. This forger is sometimes called the Toronto Group, but there 's no indication that there was anyone behind this other than a single individual making poor- and medium-quality cast copies in his basement, and the Toronto Forger is a more fitting name. The Toronto Forger brazenly put up on eBay several dozen of the same cast fakes with each round of his scam auctions, with new fakes added as he went along, mostly using the same photos. He created more than 40 rounds of scam auctions, using a different eBay I.D. each time.

Despite many people contacting it, eBay had no mechanism in place to act in a timely way. With every round of scam auctions, eBay canceled this forger 's eBay I.D. (NARUed him, for Not a Registered User), but until near the end of this forger 's run it generally wasn 't until after the auctions were over and most people had likely already paid and received their items. eBay sent messages to the people who had been scammed, but its intent was to absolve itself of responsibility. The message contained the following language: "eBay is only a venue, and we cannot guarantee that sellers will complete transactions nor can we guarantee the delivery or quality of bought items." Estimating conservatively, the Toronto Forger scammed 1,000 people out of $150,000. This scammer seems to have ceased operations, but a number of other crooks have come along and emulated his tactics. eBay has gotten better at stopping the most blatant forgery scammers, but it appears to be a sporadic effort. Other forgery scammers have made businesses of selling fakes of ancient coins and artifacts as authentic on eBay, like the Toronto Forger operating for years, only less brazenly.

You shouldn 't count on eBay to prevent or stop the auction of even the most blatant modern or ancient counterfeits or prevent sellers with a history of selling large numbers of counterfeits from engaging in online fraud. eBay is run in an extremely laissez-faire manner and enforces a policy of noninterference in its auctions, with its motive appearing to be the maximization of profits. It still doesn 't read or act upon most messages sent to it, including those alerting eBay that a seller is breaking eBay 's own rules, such as the one that prohibits sellers from disclaiming knowledge of authenticity. eBay at one point announced it was teaming with the American Numismatic Association (ANA) to make eBay safer, but after several years the ANA quit this partnership because eBay largely ignored its warnings as well. eBay also recently made it impossible to contact bidders, which previously was how people in the eBay community warned one another of a scam auction underway despite the fact that eBay had considered this auction "interference."

Good deals can be had on eBay, for both buyers and sellers, with eBay 's still relatively low (but ever-increasing) fees and its elimination of traditional middlemen. But eBay 's hands-off policies have made it a haven for counterfeit scammers, with coins, antiquities, fossils, computer software, music CDs, movie DVDs, books, paintings, clothes, sneakers, jewelry, watches, handbags, and anything else that can be faked. Such scammers operate openly on eBay. One credible estimate is that 10 percent of all ancient coins and half of all antiquities auctioned on eBay are modern forgeries. Because eBay makes it so easy to get away with fakery, one good piece of advice is to never buy on eBay ancient coins or antiquities, which are relatively easy to fake and foist on the unsuspecting, unless you 're expert in the area, know the seller, or have received a recommendation about a particular seller from a reliable source. The same is good advice with other Web sites as well.

Despite the reality of fakes in the numismatic marketplace, you shouldn 't indiscriminately, and irresponsibly, condemn coins you see online -- online pictures often provide only a fraction of the information you need to properly evaluate a coin 's authenticity. But there 's nothing wrong with questioning a coin online. To experienced eyes a fake is sometimes apparent from a photo alone. If others feel the coin is not suspicious, the seller of the coin will undoubtedly wind up with favorable publicity, and this can lead to more bids and a higher selling price.

The coin industry prefers not to talk too loudly about the issue of counterfeits for fear of scaring off collectors, sold on eBay and elsewhere, with ancient as well as modern coins. Coin dealers are also typically reluctant to publish information about fakes or even make fakes they come across available for others to study because they want you to come to them for vetted coins instead of thinking you can vet coins yourself that you buy from other collectors. But knowledge is power. Not all dealers have the same authenticity expertise, and as a collector the more you know, the greater the chance you 'll avoid getting taken. Don 't overreact and run away. But don 't put your head in the sand either. Perhaps the best approach is to look at avoiding counterfeits as the same kind of enjoyable challenge as finding good deals.

Ownership of Counterfeits

The study of counterfeits can actually be an enjoyable part of the hobby of collecting coins, ancient as well as modern. Some collectors enjoy creating a "black cabinet" (also called "black museum") of counterfeit coins for educational purposes, as help in counterfeit detection, and as examples of the black art of counterfeiting. In his American Numismatic Association (ANA) video titled "Famous Fakes and Fakers," Ken Bressett, editor of A Guide Book of United States Coins (the Red Book) and past president of the ANA, points out that some counterfeits can be considered "true numismatic items" that are "enjoyable to study and collect."

Counterfeit coins have always been an interesting aspect of the history of both numismatics and the larger world of money, just as counterfeit currency is today. Lots is at stake, then as now. For much of history counterfeiting was punishable by death. Counterfeiting has also been used, by the U.S., Britain, and many other countries, as a weapon of war against other countries. Today counterfeiting is used by terrorists as one of the means to finance their operations, though there are organized crime groups and petty crooks working alone, having nothing to do with terrorism, who are also involved with counterfeiting.

The issue of ownership of counterfeit collectable coins, however, is a controversial one, more so with U.S. coins, which are still legal tender regardless of their age, than ancient coins. The American Numismatic Association recommends that you turn in counterfeit coins to it or the U.S. Secret Service. The agent at Secret Service headquarters who heads up its anti-counterfeiting activities also advises the same thing.

Though the legalities regarding ownership of bogus coins aren 't completely clear, there 's nothing in the statutory or case law in the U.S. that indicates simple possession is illegal. Two areas of U.S. statutory law deal with counterfeit coins. Title 18, Part I, Chapter 25 (Counterfeiting and Forgery) of the U.S. Code, Sections 485, 489, and 492 deal with counterfeits of U.S. and world coins. The Hobby Protection Act of 1973 (Title 15, Chapter 48, Sections 2101 through 2106 of the U.S. Code, plus 1988 amendments) deals with counterfeits of ancient coins.

Similarly, no court in the U.S. has ever ruled that possession of counterfeits of collectable coins is illegal. What 's more, at least two circuit courts have ruled that possession of counterfeit coins without intent to defraud doesn 't violate the section of the U.S. Code on counterfeiting U.S. coins (United States v. Cardillo, 708 F.2d 29 [1983], and United States v. Ratner, 464 F.2d 169 [1972]), according to collector and lawyer Michael Benveniste.

"The statutes do not criminalize mere possession of counterfeit money," concluded Armen R. Vartian in a November 5, 2001, Coin World column titled "Owning Counterfeits." As a lawyer, numismatist, Coin World legal columnist, and author of the book A Legal Guide to Buying and Selling Art and Collectibles, Vartian is the most visible numismatic legal expert in the U.S.

All this hasn 't stopped at least one non-lawyer from amateurishly combining unrelated statutes and court cases and repeatedly pronouncing online that possessing counterfeit coins is illegal and then offering the loopy warning that if you drive with one, to a coin club meeting or from a coin show, for instance, your car may be seized by the government. There 's no indication, according to reports and the literature, that anyone has been arrested, fined, jailed, or had their transportation seized for possession of a counterfeit coin without intent to defraud in the U.S. since the Secret Service, an agency of the U.S. Treasury, began policing against counterfeits in 1865, and there 's no indication that the Secret Service plans to reverse this policy of a century and a half.

Others have also weighed in with their views about the legalities, online and in print. But ultimately it 's all just opinion, with the only opinion ultimately mattering being that of a judge, judges, or jury in a relevant case.

What is clear is that it 's illegal to possess counterfeit coins if your intention is to cheat others with them by selling them as genuine or to refuse to surrender them if the government asks you to, which it 's entitled to under the law. The Secret Service, in fact, has confiscated high-visibility collections of counterfeits of U.S. coins, and though this hasn 't happened in some 30 years, the possibility does exist that it could happen again. This gray area is the reason that Vartian and others recommend that those who maintain black cabinets of counterfeit coins do so quietly.

Hundreds if not thousands of collectors, dealers, and auction houses do just that, keeping counterfeits of collectable coins, minted from ancient times to the present, on hand for help in counterfeit detection and as examples of the black art of forgery. What 's more, counterfeit coins are bought and sold openly as counterfeits, described for what they are, every day on eBay as well as at major national coin shows and by the most respected U.S. and European numismatic auction firms.

The ownership of counterfeits of collectable coins is a non-issue today in the eyes of the authorities, who understandably devote their resources primarily toward going after those who make or pass fake bills, which can threaten the country 's money supply and ultimately its fiscal health. The Secret Service made 29,000 arrests for counterfeiting U.S. currency in the five-year period between 2003 and 2008, according to a Forbes Magazine article, while making no reported arrests for owning counterfeits of collectible coins.

Still, collecting counterfeits isn 't risk free. The main risk is that someone down the road, perhaps one of your heirs, may mistakenly sell the counterfeit as an authentic coin. This is the reason that coin collectors who elect to keep counterfeits of collectable coins should clearly identify them on the labels of their holders, says Robert W. Hoge, former curator at the American Numismatic Association, current curator at the American Numismatic Society. Another risk is that those obtaining counterfeits, purportedly to study, will turn around and try to cheat others with them by selling them as authentic. This is the reason that those dealers who do sell them are more likely to part with obvious fakes than deceptive ones and that many won 't part with any if they don 't know you.

Protecting Yourself from Fakes

The most commonly repeated advice to avoid getting cheated by unwittingly buying a counterfeit as an authentic coin is to buy from a respected dealer or auction house who offers a lifetime guarantee of authenticity with return privileges. You can learn who the respected dealers are by asking around online.

The situation becomes more complicated with European coin auction houses, even the most reputable. According to the language in their catalogs, most offer a very limited authenticity guarantee, typically lasting only about a week, which is generally too little time to send the coin out for another opinion. The best of these firms do an excellent job of screening out fakes in the first place or removing them from their auctions when the fakes are disclosed to them before the auction closes. And it has been said that they will honor the return of a fake beyond their guarantee period. But there have also been reports of difficulties returning coins when an auction house disputes the condemnation of a particular piece.

In the age of the Internet, deals can often be had through eBay buying from fellow collectors who are upgrading their coins or otherwise selling them off or buying ancient coins from direct sellers personally bringing them into the U.S. from Europe. Even here, though, sellers should offer a lifetime guarantee of authenticity with return privileges in case the coin later turns out to be fake.

With both modern and ancient coins, you should be especially wary of sellers who claim to be selling coins from an estate and who don 't offer return privileges. Similarly, avoid sellers who say they can 't guarantee a coin 's authenticity (this is against eBay rules but still happens, with sellers trying to plant the idea in bidders ' minds that they just might get a real bargain).

If you have any suspicions, don 't bid. The old maxim applies: "If a deal looks too good to be true, it probably is." (See "Coin Fraud" at the bottom of this page for more tips on avoiding eBay fraud.)

Counterfeit Detection

The most common reason a coin is condemned by an expert as being a forgery is, "It doesn 't look right." Dealers who 've handled many thousands of authentic coins are usually (not always) able to pick out fakes, even if they 're not always able to verbalize why. Part of this involves knowing what authentic coins of a particular type typically look like. Part of this involves knowing what counterfeits typically look like.

Indications of a cast counterfeit:

With clay, sand, and plaster casting, soapy or slippery surfaces, soft or missing details, and round, mushy boundaries where the devices and legends meet the coin 's field (the angle should be close to 90 degrees). However, these characteristics may not be present or present as visibly in high-quality casts made with other methods, including lost wax casting (can be used in conjunction with other casting methods), pressure casting, centrifugal casting, and vacuum casting. A seam around the edge where the two sides of the mold joined together. However, depending on the casting method used, the seam can be removed before or after the coin is cast. If removed afterward by filing and polishing, filing or polishing marks are sometimes visible, particularly under a microscope, and the edge often winds up too smooth or flat. On the other hand, ancient coins made from cast flans may show evidence of a casting seam. Small pits into the coin 's surface or small bumps rising up from it, both caused by air bubbles created during the casting process. However, these artifacts may not appear if pressure, centrifugal, or vacuum casting was used. Also, genuine coins often show some pitting, or porosity, caused by corrosion, though these pits are typically sharper at their edges, wider at their openings, and less round than pits caused by casting. Genuine coins can also have small bumps if made from rusty or worn dies. Another cause of bumps, or lumps of metal, on an ancient coin 's surface are deposits from other silver coins that the piece in question was buried with. If they flake off easily when pushed with a scapel, this indicates deposits. If they 're instead an integral part of the coin, this is a sign of casting. A casting sprue, or protuberance at one point on the coin 's edge, where metal was pored into the mold. This can also be removed by melting or filing and polishing. As with a casting seam, ancient coins made from cast flans may show evidence of a casting sprue. Light weight (or sometimes too heavy). However, genuine ancient coins often exhibit a fairly large range of weights, more so with bronze coins than silver coins, more so with silver coins than gold coins. Slightly concave obverse and reverse and smaller diameter caused by shrinking of the molten metal as it cools. However, shrinkage can be compensated for by using oversize molds, particularly with ancient coins. What 's more, genuine ancient coins exhibit a range of flan sizes and shapes. The existence of the an identical coin -- not only one made from the same dies but also one with the same centering, strike (including flan cracks), wear patterns, and surface damage (scratches, pits, corrosion). However, forgers may retouch molds to remove surface damage or add marks and alter patination/deposits on the cast 's surface. If a coin has cracks in its surfaces, as ancient coins often do, the cracks will likely have smooth edges, not sharp, visible particularly under a microscope, even with high-quality casting. With cast fakes, the insides of tiny flan cracks will also have filled in. The absence of luster, or flow lines, from striking, visible particularly under a microscope, which can be present even on worn coins, modern as well as ancient. Unless the flow lines were removed through extreme wear, corrosion, or harsh cleaning, they should be visible at protected areas of an authentic coin 's surface -- inside letters and at the edges of inscriptions and devices. Harsh cleaning to the point of smoothing, which can hide evidence of casting. However, many genuine coins have been harshly cleaned as well. A different ring from a struck, authentic version of the same coin when tapped with another coin or spun on a table. This difference results from the metal in a struck coin being compressed during the striking process and the metal in a cast coin being more spongey. However, genuine coins can ring differently (see section below titled "Ring test").

Edge seam in the form of a straight line (may be filed off) Discoloration and/or indention from the solder on the edge of the coin where the two halves are joined Over-smooth surfaces Light weight (or sometimes too heavy)

Indications of a struck counterfeit:

Unrealistic styling of devices and legends. When dies are cut by hand, it 's generally more difficult for forgers to get legends right than devices. However, dies created with authentic coins (transfer dies) won 't exhibit these problems. Die match of a known forgery Light weight (or sometimes too heavy) Wrong metal With ancient coins, the absence of any crystallization (see section below titled "Ring test"). However, some counterfeits are artificially corroded and aged with acids or struck with ancient metal. And forgers can create crystallized surfaces and interiors by preparing the planchet a certain way. With ancient coins, the absence of surface deposits, the presence of artificial, unrealistic deposits, or the absence of signs of deposits having been cleaned off the coin 's surface With ancient coins created using a modern hydraulic press rather than being struck by hand with a hammer, overly flat and uniform fields, flan of uniform thickness, edge cracks that are on the coin 's surface rather than penetrating into the coin 's interior, smaller and more triangular die cracks, long rather than short flow marks, and -- sometimes though not always -- lettering that 's evenly raised around the circumference of the coin. However, alteration by abrasion, etching, chemical degradation, or coatings can hide some indications of pressing. Double striking or die slippage, which typically shows up as subtle or blatant ghosting at the edges of devices, is an indication of striking, though it can be ancient or modern. With ancient coins created using a modern engraving machine rather than being cut by hand, deep uniform cuts at the boundaries between fields and devices and legends. However, sometimes forgers flatten the slope of the cuts, in which case you can often see tiny nicks at the boundaries between fields and devices and legends. With modern as well as ancient coins created with a transfer die, examples of which are a cast die, electroplated die, and explosive impact die (also called a blast cast die), the same or similar post-strike defects in the coin used to create the die. However, sometimes dies are slightly reworked to prevent this. With coins created with a transfer die, slightly more softness than in the coin used to create the die. However, softness can exist in an authentic coin that was struck from worn dies or weakly struck. With ancient coins created with a transfer die, slight gaps in the device or a combination of well-struck high points and poorly struck low points, both caused when the authentic coin didn 't impress far enough into the die to completely transfer all details.

Testing

There are also various quantitative tests you can do, or have done, to help with counterfeit detection. Often, any one test or several tests aren 't conclusive, but they can provide important information.

1. Weighing a coin, then comparing it with the common weight range for that coin.

2. Measuring a coin 's diameter, then also comparing it with the common range for that coin.

3. Touching a U.S. silver coin with a magnet. No authentic U.S. silver coins contain iron, so even a slight attraction to the magnet indicates the wrong alloy.

This is a useful if not infallible test. You need to compare a coin 's weight in two different media, such as air and water, using a precision scale. However, accuracy can be compromised by tiny air bubbles adhering to the coin 's surface. With ancient coins, accuracy can be further compromised through internal porosity, voids within the coin 's interior, and diagenetic leaching. The latter is a process of physical and chemical change in deposited materials over time, which can cause density to decrease or even increase through silver purification or compression or through the infiltration of lead into a coin 's fabric.

Modern silver coins typically ring when you tap them with another coin or drop them on a table, emitting a longer-lasting, higher-pitched sound. Modern non-silver coins and ancient silver coins don 't, emitting a shorter-lasting, lower-pitched sound. With ancient coins, the reason is crystallization (also called intergranular corrosion, reticulate corrosion, granularization, or embrittlement), which results when relatively pure silver alloys leach copper, lead, or other impurities over time, causing voids between the silver grains. You can often see small perpendicular ridges or swirling patterns on the surfaces of highly crystallized coins or feather-like crystals under magnification, though other times the crystallization is completely internal and invisible. The metal isn 't actually becoming crystallized; rather, its crystalline structure is being revealed by natural forces over time.

To perform a ring test, balance the coin on the tip of your finger and tap it gently with another coin. With modern coins, you can wear a cotton glove to prevent fingerprints. You need to be careful you don 't drop the coin or tap too hard. Highly crystallizedancient coins can break easily. If the coin emits a long resonating ring, like a bell, this indicates that it 's a modern silver coin. If it 's an ancient coin, this indicates it hasn 't become crystallized, that it 's likely a modern forgery, because crystallization dampens the ring. If the coin rings for only a second or two, this indicates it may be only slightly crystallized. If the coin emits a tink and doesn 't resonate, this indicates it may be moderately crystallized. If the coin emits a thud, this indicates it may be heavily crystallized.

The ring test is far from foolproof, however. Sometimes forgers use the flans of authentic, though inexpensive, ancient coins to produce old-metal counterfeits of expensive ancient coins, but this typically happens only with rare or otherwise pricey specimens. Forgers can also create crystallized surfaces and interiors with both struck and cast fakes by playing with temperatures. Counterfeits made of new silver having small, thick flans don 't resonate as well as larger, thinner coins. Counterfeits made of new silver may not ring at all if the flan is cracked, occluded with a gas bubble, or filled with another substance. Cast or electrotype counterfeits made of new silver also may not ring. Heavily alloyed silver coins made with significant amounts of bronze, lead, or other base metals will also not ring like pure or nearly pure silver coins. Nonetheless, a long resonating ring is a good indication that a coin is modern and struck.

5. Touch testing

Cast forgeries often have slippery or waxy surfaces, which can be detected with the coin in hand. Struck coins have surfaces that are more resistant to moving your finger gently over their surface. This and other touch testing is more appropriate for ancient coins than modern coins, particularly those in higher grades.

The slippery surfaces of cast coin result from microscopic "balls" of metal on the surface of metal, smaller than is visible even under a standard microscope but perceptible to the touch. Striking flattens these balls.

Touch testing can also be used to distinguish a counterfeit of an ancient coin made in ancient times, most often called a fourree, from a genuine or official ancient coin. Fourrrees are plated fakes, typically silver plating over a bronze interior or gold plating over a silver interior but sometimes either silver or gold plating over a lead interior.

Fourree detection is easiest when the plating has partly corroded away, revealing the interior metal. When it hasn 't, weight is the most commonly used test, with fourrees having bronze interiors being lighter than official coins. But some fourrees are of the correct weight, having been made using a larger or thicker flan or an interior made wholly or partly with lead. Specific gravity testing can be helpful in some cases, the exception being fourrees with lead interiors.

Another way to check if an ancient silver coin is a fourree is to feel it. Because silver is a much better heat conductor than copper, pure silver coins will feel cooler to the touch than silver-plated bronze or lead coins. The silver coin will be more effective in drawing heat away from your skin. You should test a questionable coin against a known good coin of the same type and the same denomination.

One further method is to look for edge cracks. If you find one, poke a straight pin into it and scratch away a tiny amount of metal. If the underlying metal inside the crack is orange, that indicates a gold or bronze core. If the metal is gray but soft, that indicates a lead core. If the metal is gray but hard, that indicates a silver core. The pin prick, inside the edge crack, won 't be visible unless you look inside the crack.

6. Laboratory testing

There are various nondestructive high-tech tests you can have done at some universities or commercial testing labs to analyze the metallic composition of a coin, often called elemental analysis, which can be helpful in authentication. The cost can range from $15 or less to several hundred dollars, depending on the type of test and the policies of a particular university.

The most common are the spectroscopic tests, which typically bounce radiation or subatomic particles off the surface of a coin to produce an x-ray signature, with each element that makes up the coin having its own distinct signature. In this way, you 're able to determine the percentage of each element that makes up the coin.

Various names for high-tech tests are used in the literature, some of which refer to the same type of test, and include:

X-ray fluorescence (XRF), also known as energy dispersive x-ray fluorescence (EDXRF) -- a surface technique, reaching depths of between 30 and 100 micrometers, that puts x-rays in and analyzes x-rays that come out; most commonly used metallurgical analysis technique used in numismatics Energy dispersive spectroscopy (EDS), also known as electron dispersive spectroscopy, energy dispersive x-ray spectroscopy (EDX), or scanning electron microscopy with energy dispersive x-ray spectrometry (SEM-EDS or SEM/EDX) -- a surface technique that puts electrons in and analyzes x-rays that come out Proton induced x-ray emission (PIXE), also known as particle induced x-ray emission -- a surface technique that puts protons in and analyzes x-rays that come out; goes deeper than XRF and EDS and allows for the detection of trace elements; expensive Proton activation analysis (PAA), also known as proton induced gamma ray emission (PIGE) -- a surface technique that puts protons in and analyzes gamma rays that come out; goes deeper than XRF and EDS and allows for the detection of trace element; expensive Secondary ion mass spectrometry (SIMS), also known as charged particle activation analysis (CPAA) -- a surface technique that puts ions in and analyzes ions that come out; goes deeper than XRF and EDS; highly accurate; removes some material from the test coin Neutron activation analysis (NAA), also known as nuclear reaction analysis (NRA) -- puts neutrons in and analyzes gamma rays that come out; penetrates the entire body of the coin; allows for the detection of trace elements; doesn 't detect lead; leaves the coin slightly radioactive; expensive

These tests are useful but not infallible. Most of these tests analyze coins only to a depth of slightly below their surface, which can compromise the results in the event of heavy toning/patination, corrosion, or surface enrichment, though this can often be avoided by preparation of the small part of the coin 's surface that 's being analyzed.

The most accurate testing is wet chemical testing. In the past, this required that the coin be destroyed, which limited its usefulness. A newer method involves drilling a minute hole in the edge and wet analyzing the slight amount of metal extracted. Though this also is destructive, a tiny hole in an edge crack wouldn 't be noticed with an ancient coin. It 's reportedly an accurate but expensive testing methodology.

Metallurgical analysis can be helpful if the alloy doesn 't match the known alloy of the coin. If the alloy is variable, as it is with medieval and ancient coins, metallurgical analysis can help if the alloy is significantly off or precisely matches a known modern alloy.

Metallurgical testing can be defeated by moderately skillful forgers who create fakes made of the correct alloy. With ancient coins, this can be done using ancient metal such as inexpensive coins that are melted down to make fakes of expensive coins. In these cases, other diagnostics must be used.

Metallurgical testing, on the other hand, can be useful also for learning more about authentic coins. But here too it has its limitations. In ancient times the same coin type could have used gold or silver from different mines. The metal from a single mine could vary in composition depending on which vein it came from. And coins could be made from other coins, prior coins from that region or contemporaneous coins from other regions, that were melted down.

Learning about counterfeits can be fun, in addition to protecting you. The following are books about counterfeit U.S. coins (and in some cases other coins as well). For details, see the descriptions and reviews at Amazon.com.

The following are two e-mail discussion groups, one Web-based discussion area, and one Usenet discussion group where counterfeit coins are discussed online:

CoinForgeryDiscussionList (CFDL)This e-mail discussion group, a Yahoo Group, is the largest online discussion group devoted to solely counterfeit coins, but it 's extremely controversial. Much discussion involves the condemnations of fakes from blatant eBay scammers, a useful service. Sometimes high-end mistakes from large auction houses are outted as well, another useful service, one that the coin establishment doesn 't provide to collectors. Unfortunately, the information published there is frequently unreliable. One expert authenticator who used to participate in the group said the false positive rate is about 50 percent, meaning half of the coins labeled as fake are not.

What 's more, the actions of group leaders are frequently irrational. The group is populated to a disproportionate extent by amateur numismatists posing as experts, conspiracy theorists who feel that the coin establishment deliberately cheats collectors, and people with an agenda against other dealers. Criticism of dealers other than the group 's founder is encouraged, but participants who express opinions opposed to the practices of those who run the group or in disagreement with their views are shouted down, censored, or banned from the group, with the most common rationale offered being that they 're criminals employed by forgers. Yet the group 's founder has admitted to salting the ancient coin marketplace with forgeries to "test" other dealers and feels that it 's OK for dealers to sell forgeries as authentic coins if they can 't easily be detected. He has said that the world 's premier numismatic dealer organization, the International Association of Professional Numismatists (IAPN), is controlled by criminals. He set up another forgery discussion group through eBay but contended that eBay began censoring it after criminals lobbied and/or bribed eBay.

To try to provide some balance against the irrationality, the hooliganism, and the errors of CFDL, a few seasoned numismatists occasionally participate in the group, but often they 're just shouted down, with most having left. According to one ancient coin dealer active online, CFDL and its reputation are what 's primarily responsible for many ancient coin dealers not participating in online dicussion groups in general. CFDL is an understandable reaction, or overreaction, to attempts by many in the numismatic establishment to damper discussion about the counterfeit issue. There are benefits to following CFDL, but if you do, take what 's there with a large grain of salt. It can be an interesting window into the dark side of numismatics from a number of different angles.

ACFDL (Ancient Coin Forgeries Discussion List)This Yahoo Group doesn 't receive nearly as much traffic as CFDL, but the discussion is more balanced and considerably more scholarly. It deals strictly with ancient coin forgeries.

FORVM 's Fake Ancient Coin Reports and DiscussionThis is the most active and useful Web-based discussion group about ancient coin forgeries. It includes a forgery database. The discussion there in general is scholarly, balanced, fair, and reliable. It 's populated by seasoned experts as well as relative newcomers.

Rec.collecting.coinsThis Usenet discussion group, about coins in general, can be a good resource for getting opinions about questionable U.S. and other modern coins.

More Information

Counterfeit Coin Bulletin/Bulletin on CounterfeitsPeriodical about U.S., world, and ancient counterfeit coins that most recently was published jointly by the American Numismatic Association (ANA) and the International Association of Professional Numismatists (IAPN). Before 2000, as the Bulletin on Counterfeits, it was published solely by IAPN. This periodical began publication in 1976, but the ANA and IAPN suspended publication after the December 2002 issue, an unfortunate decision for the coin collecting community. You can find partial indexes of past issues at Robert Matthews Coin Authentication and Lakdiva Coins. The IAPN now restricts its counterfeit information primarily to member dealers. It has indicated it will publish press releases about counterfeits for the numismatic public, but thus far this effort has been extremely limited.

Counterfeit Coin NewsletterSemiannual free online periodical from Robert Matthews Coin Authentication about modern and ancient counterfeit coins, though Mathews ' focus is primarily on UK coinage.

CounterfeitQuarterly membership periodical from the Counterfeit Coin Club, based in the UK. The president of the club, Ken Peters, is the author of the book The Counterfeit Coin Story.

Here are some other Web pages I 've put together about counterfeit coins, U.S. and ancient:

Ultimately, as long as you 're careful, you shouldn 't fret over the possibility of getting fooled by counterfeits. As Sayles points out, virtually all serious collectors of ancient coins, for instance, will sooner or later unwittingly add a fake to their collection, and this is not necessarily a sign of naiveté. With U.S. coins, the grading services have greatly reduced the chances of being cheated with high-end specimens.